A considerable degree of atmospheric pollution occurs through the ordinary burning of a hydrocarbon fuel mix in the normal combustion engine. Various means have been devised however for minimizing the discharge of harmful emissions into the atmosphere from such engines. The concomitant and optimum desire is to operate the engine in a manner such as to fully utilize the fuel burned therein, and yet achieve the desired minimization of harmful discharges.
These atmospheric pollutants comprise among other things, the exhaust or combustion gases. At least one harmful component of said gases is the NO.sub.x component. It has been determined, that to a large extent the degree of NO.sub.x produced by an engine has a direct correlation to the temperature of the exhaust gas. At higher exhaust and gas temperatures, the amount of resulting NO.sub.x is found to be considerably greater than at lower engine operating temperatures.
Toward minimizing the amount of NO.sub.x produced through an engine exhaust gas recycling process, it has been determined that with proper forming of a homogeneous inlet charge, said proportion of exhaust gas can be greatly increased. It is understood however, that under particular engine operating conditions the amount of exhaust gas which can be feasibly utilized in the charge will vary. For example, at higher engine loads, the percentage of exhaust gas recycled is reduced if efficient engine operation is to be realized. On the other hand, at lower and engine idle speeds, said proportion of exhaust gas can be substantially increased.
More specifically, it is known that a recycling of up to approximately 10 percent of the produced exhaust gas will permit an efficient operation of the engine. Beyond this percentage of recycled gas, engine efficiency falls off with the result that the amount of hydrocarbon produced, substantially increases, while the engine output horsepower decreases.
The desired mixing of exhaust gas with atmospheric air to form the homogeneous preliminary charge, is achieved at least in part, through the use of the herein described gas mixing element. Said mixing element receives flows of first and second gases, which will be hereinafter referred to as the exhaust gas and atmospheric air respectively. While other combustion supporting gases can also be utilized in place of atmospheric air or to supplement the latter, the normal engine operation will utilize air as the main ingredient in the combustible mixture.
Functionally, the discrete gases are introduced to a common mixing compartment where they are prompted to form the desired homogeneous mixture. However, the means for introducing said gases includes passage of the exhaust through a plurality of adjacently disposed constricted nozzles. The spaces defined intermediate said respective adjacent nozzles define a plurality of passages for the entrance of atmospheric air. Thus, the latter is drawn into the mixing compartment along the walls of the adjacently disposed nozzles such that the velocity of the respective air and gas are substantially compatible. Thereafter, upon mixing of the two media, the substantially homogeneous mass will be withdrawn through an exhaust port and directed to the intake side of the combustion chamber for introduction to the latter.